The tennis season has begun with Rafael Nadal, Ash Barty, Paula Badosa and Thanasi Kokkinakis among the champions at small-scale events in Australia.

Yet there has been one dominant story in the sport and little else has had a look-in in the lead-up to the Australian Open.

Now that Novak Djokovic knows his fate, there is the welcome prospect of eyes turning to matters on the tennis court, rather than the Federal Court.

With the action getting under way in Melbourne on Monday, Stats Perform looks at the main protagonists and what the numbers tell us about another high-stakes grand slam.

Djokovic absence blows open men's draw

As defending champion Djokovic heads for home, it is worth a reminder of how he has dominated this tournament.

Nine of his grand slam titles have come in Melbourne, and he has taken the trophy in each of the last three years, helping him cosy up alongside Roger Federer and Rafael Nadal on 20 majors, an all-time record they share. Of the 'Big Three', only Nadal is in the draw this year, with Federer currently on the injured list.

Djokovic has the highest win percentage in the Open Era (since 1969) at the Australian Open, among players with 20 or more wins (91.1 per cent – W82 L8). He was hoping to join Nadal (13 French Opens) and Margaret Court (11 Australian Opens) in the exclusive club of players to reach double figures for singles titles at one slam.

The Serb was also aspiring to become the first man in the Open Era to win four consecutive Australian Opens. It happened once before the tour turned professional, with Roy Emerson winning five in a row from 1963 to 1967. Djokovic has left Melbourne with the title every time that he has made it through to the semi-finals.

So who takes the title now?

Only Bjorn Borg (89.2 per cent) has a higher winning percentage in grand slam matches than Nadal (87.7 per cent) and Djokovic (87.5 per cent) in the Open Era, among players with 100 or more wins. So why not Nadal?

The 35-year-old and Djokovic have carved up 12 of the last 14 grand slam titles, Nadal winning four of those (three French Opens, one US Open). He is battling back from a foot injury lay-off and coronavirus, and might need to get the early rounds out of the way without undue stress to stand a chance at the business end.

The two exceptions in the Nadal-Djokovic sequence of slam dominance have come at the US Open, with Dominic Thiem winning in New York in 2020 and Daniil Medvedev triumphing at Djokovic's expense in last year's Flushing Meadows final. Thiem is not in Australia, but world number two Medvedev is, looking to become the third Russian man to win two slams, after Yevgeny Kafelnikov and Marat Safin.

The last man other than Federer, Nadal and Djokovic to secure back-to-back slam singles title was Andre Agassi (US Open 1999 and Australian Open 2000), but that is Medvedev's objective now, and he has the game to pull it off.

Nadal has reached at least the quarter-final stage in 15 of his last 16 grand slam appearances, winning six of those majors (four French Opens and two US Opens), so he may well be a factor.

Who else is in the frame? Alexander Zverev probably, having reached the quarter-finals in Australia in the last two seasons (SF in 2020 and QF in 2021). He won the Olympic Games and ATP Finals titles last year, so a grand slam is an obvious next step. He might want to keep double faults in check though, having served a tour-high 113 in slams last season.

Stefanos Tsitsipas reached the Australian semi-finals in 2019 and 2021, so throw him into the mix too, and Matteo Berrettini might be a threat. The Italian, a runner-up to Djokovic at Wimbledon in July, served more aces than any other player in grand slams last year (311 aces, 16.4 on average per match).

Others have more modest ambitions

Andy Murray is back at the Australian Open for the first time since 2019, when he lost in the first round against Roberto Bautista Agut in five sets and was more or less given his last rites as a tennis pro after the match, having indicated he was close to retirement.

The five-time Australian Open runner-up last won a match in this tournament in 2017, when he reached round four. A tough opener against Nikoloz Basilashvili awaits.

Spanish 40-year-old Feliciano Lopez will make his 80th appearance in a grand slam and become the second man in the Open Era with 80 or more appearances at the four majors, after Federer (81).

Do not expect an Australian to be men's champion, by the way. The last time an Australian reached the men's singles final was 2005, when Lleyton Hewitt lost against Safin, and the last home champion was Mark Edmondson in 1976.

Barty backed in stacked women's draw

For the first time since 1997, neither Serena nor Venus Williams will take part in the Australian Open. Yet the women's tour is in rude health, even without those great bastions.

Ash Barty is world number one and a standout pick for many, only enhancing her claims after winning an Adelaide International title in the run-up to this fortnight.

But there is staggering depth on the women's side at present, and Barty will face stiff competition.

Incredibly, the last five grand slam finals have featured 10 different women, and teenager Emma Raducanu's against-all-odds US Open triumph in September shows best of all that new stars are emerging.

Yet since 2000, only three non-seeded players have reached the women's singles final at the Australian Open: Serena Williams in 2007, Justine Henin in 2010 and Garbine Muguruza in 2020. 

Barty could become the first Australian to be women's champion since Chris O'Neil in 1978, and the first to reach the final since Wendy Turnbull lost to Hana Mandlikova in 1980.

The Queenslander is the top seed, and the last time the number one failed to reach at least the fourth round at Melbourne Park was in 1979, when Virginia Ruzici lost her opening match. Barty ended a long wait for an Australian winner of the women's title at Wimbledon last year, so why not closer to home as well?

Naomi Osaka is back, so what should we expect?

Truth be told, that's hard to know. Osaka took time out from tennis after the US Open to focus on her mental health and enjoyed hanging out with friends, before deciding she missed tennis enough to go back on tour.

She had three wins at the Melbourne Summer Set tournament recently before withdrawing from a fourth match, saying her body had "got a shock" from the intensity. As defending champion in the season's first major, she has a target on her back and will need to find a way to handle that.

Over the past six seasons, only Osaka has managed to win back-to-back grand slam singles titles among the women, and she has done so twice (US Open 2018 and Australian Open 2019, plus US Open 2020 and Australian Open 2021).

The last player to win back-to-back women's Australian Open singles titles was Victoria Azarenka (2012 and 2013), so it does not happen regularly.

Osaka has an 85 per cent win rate at this tournament: since 2000, only Jennifer Capriati (90 per cent) and Serena Williams (89 per cent) have had a higher win percentage in the main draw.

You want challengers to the big two? Try sticking a pin in the draw

The Daphne Akhurst Memorial Cup, which goes to the champion, is a trophy that upwards of a dozen women will seriously believe they can win.

Aryna Sabalenka has reached the semi-finals of the last two slams but is mired in some kind of hellish serving groove, having made 74 double faults in her last four matches and lost the last three in a row.

Anett Kontaveit won a tour-high 39 matches on hard courts last year but has only been to one grand slam quarter-final – last year in Australia, losing to Simona Halep.

What about Ons Jabeur, who matched Kontaveit for a tour-high 48 wins across all surfaces last year? The Tunisian is queen of the drop shot, making 147 successful such plays on tour last year, more than any other player, and recently reached the top 10 in the WTA rankings for the first time.

Maria Sakkari reached two slam semi-finals last year, the first of her career, and the form of Barbora Krejcikova and Badosa in the past week in Melbourne marks them out as contenders. Both are recent fast-risers, Krejcikova already with a French Open title to show.

WTA Finals champion Muguruza could be the second Spaniard to twice reach the Melbourne title match, after Arantxa Sanchez Vicario (1994 v Steffi Graf and 1995 v Mary Pierce). Spain has never had an Australian Open women's singles winner: former French Open and Wimbledon champ Muguruza is an authentic contender.

Halep was runner-up to Caroline Wozniacki in 2018, a semi-finalist in 2020 and quarter-finalist last year, and a Melbourne Summer Set title was a handy warm-up for the Romanian. Consider her, too.

Monica Seles, in 1991, was the last player to triumph on her debut in the main draw, but she was already a grand slam winner (1990 French Open). Given the strength of the line-up, the prospect of a bolter coming through this field is unlikely, even if the example of Raducanu tells us anything is possible.

Novak Djokovic has won the last three Australian Open titles and lifted the trophy nine times in all, which means he arrived in Melbourne as a hot favourite to triumph again.

Yet even before the chaos of the last 10 days, this looked a tough Australian Open for Djokovic, given the likes of Daniil Medvedev and Alexander Zverev have recently taken his scalp in major hard-court matches.

There was no doubt he was a worthy favourite, but Djokovic's dominance of the first half of last season was followed by a series of painful defeats, weakening his standing at the top of the game.

When the men's singles draw was made on Thursday, only two former champions featured: Djokovic and Rafael Nadal, the 2009 winner.

Here, Stats Perform assesses the contenders to follow Djokovic onto the Melbourne Park throne.

NEXT NUMBER ONE? DANIIL MEDVEDEV

Last year's runner-up, given a sound pasting by Djokovic in a final that came nowhere close to matching expectations, has come a long way since that crushing blow. Russian Medvedev was the only man to beat Djokovic in a grand slam last year, doing so at the final hurdle of the final major, without dropping a set in the US Open title match. That denied Djokovic a calendar year sweep of the majors, which would have been the first time the feat had been achieved by a man since Rod Laver's 1969 complete set.

He also took the first set off Djokovic in the Paris Masters final in November, only to lose the match. What is clear is that Medvedev is amassing experiences against Djokovic: some good and some bad, but all surely massively helpful. He lost in their first three encounters but has won four of the seven since.

Progress like this is what repeat champions are made of. Medvedev has a 9-9 win-loss record when dropping the first set of matches over the past year, which shows he is not easily beaten. Only Djokovic (14-6) has a better record in that respect.

Medvedev has a 54-9 record on hardcourts over the past 12 months, has gone mightily close to hitting number one in the rankings, and might see a lot of that top step in the months and years to come. On the 52-week rolling list, he holds a 16-8 win-loss record against top-10 opponents, which is second only to Djokovic (22-5).

Should Medvedev pull off a second consecutive grand slam win, it would make him just the third Russian man to win two or more grand slam singles titles, after Yevgeny Kafelnikov (French Open 1996 and Australian Open 1999) and Marat Safin (US Open 2000 and Australian Open 2005).

The last player other than Federer, Nadal and Djokovic to secure back-to-back majors was Andre Agassi (US Open 1999 and Australian Open 2000).

OVERDUE SLAM INCOMING? ALEXANDER ZVEREV

The Olympic champion and ATP Finals winner is just lacking a grand slam title to confirm to the wider sporting world his status as one of the rising generation's preeminent performers. Zverev beat Djokovic in semi-finals en route to both of those big 2021 titles, and although he also lost three times to the 20-time major winner over the season, he took four sets off the man from Belgrade in those defeats.

Zverev is improving season on season, and if he avoids injuries or other tribulations in 2022 then he surely stands a strong chance of picking up that first slam before the year is out. He won six titles in all in 2021, more than any other singles player on the ATP Tour, and holds a 43-10 win-loss record on hardcourts on the 52-week rolling list.

When the draw was made, he and Djokovic were set on another semi-final collision course, and that prospect looked tantalising. Until recently so far apart, the gap has closed considerably, Zverev tallying victories that will have surely troubled the world number one.

NOT READY TO BE YESTERDAY'S MAN: RAFAEL NADAL

Because why the heck not? Nadal, at the age of 35, returned from a long foot injury lay-off with a title at the Melbourne Summer Set tournament this month, and if his record at the Australian Open is deemed unspectacular by some, the Spaniard himself takes great pride in his achievements.

Recently, in a Melbourne news conference, he was asked why he had not reached the semi-finals of the Australian Open since his title year, and Nadal swiftly put his questioner right.

"I am very sorry to tell you – I don't want to – but I have been in the final of 2012, '14, '17, '19," he said. "I got injured a couple of times here in my tennis career, so of course it's been a great tournament for me, and of course I had a lot of challenges in terms of injuries in this event. Sorry to correct you."

Polite as ever, but pointed. Nadal knows he has been successful in Australia and would surely not have returned this year if he felt there was no chance of another run to the final. He rightly takes issue with those who forget his feats. Remember, he, like Djokovic and Federer, sits on 20 grand slams.

Nadal reached the quarter-finals last year and lost from two sets up against Stefanos Tsitsipas, so he will want to banish that memory. There is little evidence of hard-court form beyond his win in a mediocre field last week in Melbourne, but he is Rafael Nadal and he wins tennis tournaments. At least one every year since 2004. A 6-8 record against rival top-10 players over the past 52 weeks is no great shakes, but you count out Nadal at your peril.

NEXTGEN OR NEXT NEW CHAMP? JANNIK SINNER

Tennis is such a generation game just now. The Big Three (Big Four, if you include Andy Murray) are in the twilight years of their careers, coming under long-awaited threat from the mid-twenties likes of Medvedev, Zverev, Dominic Thiem (absent from Australia), Tsitsipas and Matteo Berrettini.

Sinner is to the forefront of the pack of the next big group coming through (see also: Carlos Alcaraz, Lorenzo Musetti). At 20, the Italian is entering a big year in the context of his career. By the time Djokovic turned 20, he was sixth in the world, Federer was 14th on the day he left his teenage years behind, and Nadal was second. Progress comes at different rates.

Sinner was 15th in the rankings on his last birthday, in August, but has since dipped his toes into the top 10 and currently stands 11th. He won four ATP Tour titles in 2021, finished the year with a 49-22 record, and can reasonably be expected to kick on. The Italian has yet to majorly show up at the grand slams, with a Roland Garros quarter-final in 2020 his best run yet.

Expect that to change soon enough. Sinner is only 6-9 against top-10 players on the 52-week list, but he warmed up for the challenge that lies ahead in Melbourne with three straight-sets singles victories at the ATP Cup. His 42-14 record on hardcourts over the last year suggests the Australian Open should suit him as well as any slam.

Twenty-time major winner Rafael Nadal says he is tired of the Novak Djokovic saga ahead of the Australian Open and insists the event will be "great" with or without him.

Sixth seed Nadal is preparing to take on American Miguel Giron in the Australian Open first round on Monday but preparations have been hijacked by Djokovic's ongoing visa status.

The world number one had his visa cancelled by the Australian Immigration Minister on Friday with an appeal to be held on Sunday.

The situation has dragged on for the past week, with Nadal admitting he was tired of the narrative and that no one player is bigger than the Australian Open.

"I tell you one thing, it's very clear that Novak Djokovic is one of the best players of the history, but there is no one player in history that's more important than an event," Nadal told reporters on Saturday.

"[The] Australian Open is much more important than any player. If he's playing finally, OK.

"If he's not playing, [the] Australian Open will be great, with or without him. That's my point of view."

World number six Nadal, who has only won the Australian Open title once in 2009, said he hoped focus would return to the upcoming tournament where he is aiming for a record-breaking 21st slam.

"Honestly, I'm little bit tired of the situation because I just believe that it's important to talk about our sport, about tennis," Nadal said.

The Spaniard added that he respected Djokovic and has a "good relationship" with him despite their differences.

"I wish him all the best. I really respect him, even if I [do] not agree with a lot of things that he did the last couple of weeks," he said.

Novak Djokovic has been drawn against Miomir Kecmanovic in the opening round of the Australian Open as the defending champion awaits to hear if he can stay in the country.

World number one Djokovic was last week given a medical exemption to enter Australia, despite not being vaccinated, only for border officials to block it upon his arrival.

The 20-time grand slam winner was detained for four days while waiting to appeal the case on Monday, which went in his favour at Melbourne Circuit Court.

Djokovic has since started training ahead of the Australian Open, which begins next Monday, though immigration minister Alex Hawke may yet cancel his visa for a second time. 

A decision on whether Djokovic can compete in the first grand slam of the year, which he has won a record nine times, could be made on Thursday.

Should he be given the all clear to take part, Djokovic will face compatriot Kecmanovic in the first round at Melbourne Park.

Thursday's draw, which was delayed by one hour and 15 minutes for unspecified reasons, also saw fellow 20-time grand slam winner Rafael Nadal paired with Marcos Giron.

Nadal is in the same half of the draw as Djokovic, meaning the pair could meet in the semi-finals, while third seed Alexander Zverev is also in the top half.

Second seed and 2021 finalist Daniil Medvedev is in the bottom half along with Stefanos Tsitsipas and will take on Henri Laaksonen first up.

In the women's draw, Australia's world number one Ash Barty will begin her quest for glory on home soil against a qualifier.

The top seed is on a collision course with defending champion Naomi Osaka, who goes face-to-face with Camila Osorio in round one on her return from a four-month break.

Reigning US Open winner Emma Raducanu is up against Sloane Stephens, who won the New York major in 2017, while Storm Sanders awaits second seed Aryna Sabalenka.

Rafael Nadal joked that he would rather Novak Djokovic does not play at the upcoming Australian Open after the world number one won his appeal to remain in the country.

Djokovic was left fighting for the right to compete at the opening grand slam of the year, a tournament he has won nine times, after authorities cancelled his visa last week.

A medical exemption was expected to allow the Serbian to enter the country, regardless of his vaccination status, which he has yet to formally disclose.

But the Australian Border Force declared Djokovic had been ordered to fly out of the country on Thursday, sparking a challenge to that decision by the tennis star's legal team.

After both sides had presented their cases, Djokovic was handed an Australian Open lifeline on Monday when defeating a deportation order brought by Australia's government

Judge Anthony Kelly ruled at Melbourne Circuit Court that Djokovic's visa cancellation order should be "quashed" immediately.

There may yet be another twist in the saga, though, as Australia's immigration minister Alex Hawke could still cancel the 34-year-old's visa on new grounds.

Djokovic now appears far more likely to defend his Australian Open crown than he did over the weekend, however, as he goes in search of a 21st major title.

While that will inevitably make Nadal's chances of success at Melbourne Park a whole lot tougher, the Spaniard said the decision to grant Djokovic's freedom must be respected.

"Whether or not I agree with Djokovic on some things, justice has spoken and has said that he has the right to participate in the Australian Open," he told Onda Cero.

"I think it is the fairest decision to do so, if it has been resolved that way. I wish him the best of luck.

"But on a personal level, I'd much rather he didn't play!"

Nadal described Djokovic's COVID-19 vaccination controversy "a circus" and reiterated that the vaccine "is the way to stop this pandemic and disaster".

The 35-year-old ramped up his preparations for the Australian Open by winning last week's Melbourne Summer Set without dropping a single set.

That was Nadal's first tournament in five months due to injury and means he has won at least one ATP Tour trophy in every season since 2004 onwards.

He is level with Djokovic and fellow great Roger Federer on 20 grand slam titles, with the trio locked in a race to finish with the most majors.

Rafael Nadal saw off Maxime Cressy in straight sets in Sunday's Melbourne Summer Set final to land the 89th singles title of his career.

The world number six, playing in his first tournament in five months due to injury, has now won at least one ATP Tour trophy in every season since 2004 onwards.

American qualifier Cressy more than held his own in a first set that went the distance, though Nadal's quality told as he prevailed 7-6 (8-6) 6-3 at Rod Laver Arena, where Nadal will be hoping to go deep in the season's first grand slam later this month.

Both men held in an entertaining opening set and Cressy led 6-5 in the tie-break, but he squandered his set point and Nadal hit back to grab a foothold on the match.

The 35-year-old, who won the tournament without dropping a single set, recovered from a break down in the second to add yet another trophy to his vast collection.

Nadal, who had not played since August before coming into this tournament and had COVID-19 last month, had not previously captured a title in Australia since 2009 when landing his only Australian Open triumph to date by beating Roger Federer.

And the Spaniard looks in good shape heading into the Australian Open, which may not feature defending champion Novak Djokovic, who is awaiting the outcome of a hearing to determine whether he will be able to compete in Melbourne.

"I feel privileged and a very lucky guy to be here again," Nadal said in his on-court interview.

"I am coming back from some challenging moments in terms of injuries, so I can't be happier. It means a lot to be back and with a trophy in my hands.

"This court has always been very, very special for me. The Rod Laver Arena is very, very special for everyone and it is more special because of you guys. You guys are a great crowd and I can't thank you enough."

Elsewhere on Sunday, Gael Monfils also made a promising start to the 2022 season with a 6-4 6-4 victory over Karen Khachanov in the Adelaide International 1 final.

Khachanov battled past former US Open champion Marin Cilic in the semi-finals, but he fell short of clinching a first title in over three years.

Top seed Monfils held throughout the opening set and found a breakthrough in the 10th game, with the second set following an identical pattern.

The Frenchman did not drop a set all tournament on his way to winning a first trophy since February 2020 in Rotterdam.

Rafael Nadal fended off a battling Emil Ruusuvuori to reach the Melbourne Summer Set final as the Spanish veteran bids to land the 89th singles title of his stellar career.

Nadal, who has won at least one ATP Tour tournament in every season from 2004 onwards, will look to extend that streak into a 19th year after scoring a 6-4 7-5 win on Rod Laver Arena.

He has not captured a title in Australia since 2009, when he landed his only Australian Open triumph to date by beating Roger Federer.

Nadal will be a strong favourite against American qualifier Maxime Cressy in Sunday's final, despite being made to work hard to see out victory over 22-year-old Ruusuvuori.

The 35-year-old Mallorcan looked set for a routine win but dropped serve at 5-3 in the second set, allowing world number 95 Ruusuvuori a path back into the contest.

It provided Nadal with a test of resolve that he came through, tying up victory in an hour and 56 minutes, an encouraging sign as he continues to battle for full sharpness after a near five-month absence.

Nadal acknowledges he may not have long left in tennis, and he wants to make the most of the opportunities that remain.

"I just love what I'm doing," he said in an on-court interview. "I always feel passionate about the sport in general and I feel a very lucky person that I can live from one of my hobbies, tennis.

"I know it's not forever and it's not a job I'm going to do for 50 years, but I want to enjoy it as much as I can while I still have the chance."

The foot injury that caused the 20-time grand slam winner to curtail his 2021 season in August has not prevented him finding winning form this week and now Paris-born Cressy awaits, with the 24-year-old world number 112 enjoying a remarkable week.

Cressy was a 7-5 7-6 (11-9) winner on Saturday against Bulgarian third seed Grigor Dimitrov, serving 17 aces on the way through to his first ATP Tour final.

At the Adelaide International 1 event, Gael Monfils will face Karen Khachanov for the trophy.

Top seed Monfils ended the spirited run of Australian wildcard Thanasi Kokkinakis, earning a 7-5 6-0 semi-final win, while second seed Khachanov battled past former US Open champion Marin Cilic 7-6 (7-3) 6-3.

Rafael Nadal was handed a walkover to the semi-finals of the Melbourne Summer Set tournament when his opponent withdrew with a foot injury.

In an ironic development, given Nadal has been so plagued by his own serious foot problems, Tallon Griekspoor had to pull out of his scheduled clash with the 20-time grand slam champion on Friday.

That was perhaps not the news Nadal wanted, given the Spaniard is competing this week to gain much-needed match practice ahead of the Australian Open. It is his first ATP Tour event since August, when a long-existing left foot problem caused him to curtail his season.

Withdrawing from a Rod Laver Arena tussle with Nadal was a painful blow to 25-year-old Dutchman Griekspoor too, and he wrote on Twitter: "These are the matches you play for."

It would have been a first career meeting with all-time great Nadal for the world number 65, who instead faces a fitness battle before the first grand slam of the year begins on January 17.

Nadal will go on to face Finland's Emil Ruusuvuori, who won 6-2 6-1 against Slovakian Alex Molcan. The other semi-final on Saturday will see Bulgarian third seed Grigor Dimitrov tackle American qualifier Maxime Cressy.

At the Adelaide International, the top three seeds sauntered through to the semi-finals. Top seed Gael Monfils brushed aside Tommy Paul 6-4 6-1, number two Karen Khachanov saw off Egor Gerasimov 7-5 6-3, and third seed Marin Cilic was a 6-3 6-2 winner over Laslo Djere.

It was also confirmed on Friday that former world number one Andy Murray has been awarded a wildcard into next week's Sydney Classic.

Murray suffered a first-round exit in Melbourne and is looking for a run of matches before launching his campaign at the Australian Open, where he is a five-time runner-up.

Rafael Nadal declared his first singles match on the ATP Tour for five months a roaring success after the Spaniard battled past Ricardas Berankis in Melbourne.

A 6-2 7-5 win for Nadal over the Lithuanian qualifier carried the 35-year-old into the quarter-finals of the Melbourne Summer Set tournament.

Playing on Rod Laver Arena, the main show court for the upcoming Australian Open, top seed Nadal was tested by Berankis but came through unscathed, breaking serve to love to clinch the victory.

This was the first time that Nadal had faced Berankis, the world number 104 who briefly entered the top 50 five years ago, and it came as the 20-time grand slam winner battles back from the left foot injury that curtailed his 2021 season.

Nadal had not competed on tour since losing to Lloyd Harris in the third round in Washington in August, and the match practice he gained at an exhibition event in Abu Dhabi last month was followed by him contracting COVID-19.

He is vaccinated though, so was able to travel once he recovered from that brush with coronavirus, and is looking to build up form and fitness before the Australian Open begins.

"Honestly, I've been going through some difficult, challenging moments the last year and a half, but in general terms I'm super happy to be back in competition," Nadal said.

"It's important to start with a victory. It gives me the chance to play another time tomorrow and that's the main thing at this moment because I didn't play for such a long time.

"The main thing is being healthy. That's probably the only thing."

Awaiting Nadal in the last-eight stage will be Dutch player Tallon Griekspoor, who fended off Australia's Alexei Popyrin in three sets.

Determined not to take on too heavy a workload, Nadal has pulled out of the doubles tournament, despite making a winning start on Tuesday when he paired up with fellow Spaniard Jaume Munar.

He elected to play doubles initially to build up some rhythm. "In doubles, things always happen fast," Nadal said. "It makes you feel alive on the tour again. I think that was a positive thing."

Third seed Grigor Dimitrov advanced, seeing off Andy Murray's conqueror Facundo Bagnis in three sets, but Belgian fourth seed David Goffin slumped to a 7-5 6-3 loss against Slovakian Alex Molcan.

At the Adelaide International 1 tournament, there were wins at the last-16 stage for the top three seeds – Gael Monfils, Karen Khachanov and Marin Cilic – but fourth seed Frances Tiafoe was caught out by Australian Thanasi Kokkinakis, losing in three sets.

Rafael Nadal declared it was imperative to "follow the rules" on COVID-19 vaccinations after rival Novak Djokovic was told he faces being deported from Australia.

World number one Djokovic was left fighting for the right to compete at the Australian Open, a tournament he has won nine times, after authorities cancelled his visa.

A medical exemption was expected to allow Djokovic to enter the country, regardless of his vaccination status, which he has yet to formally disclose.

However, the Australian Border Force declared the Serbian had been ordered to fly out of the country on Thursday, sparking a challenge to that decision by Djokovic's legal team.

Reports in Australia said an interim injunction had been granted, meaning Djokovic will remain in immigration detention until a court hearing on Monday.

According to Nadal, who had COVID-19 recently but has been cleared to compete at Melbourne Park, Djokovic would have made his life a lot easier by going down the vaccination route.

"It's normal that the people here in Australia get very frustrated with the case because they have been going through a lot of very hard lockdowns, and a lot of people were not able to come back home," Nadal said.

"The only thing that I can say is I believe in what the people who know about medicine says, and if the people say that we need to get vaccinated, we need to get the vaccine.

"I went through COVID. I have been vaccinated twice. If you do this, you don't have any problem to play here. The world in my opinion has been suffering enough to not follow the rules.

"I think if he wanted, he would be playing here in Australia without a problem. He made his own decisions, and everybody is free to take their own decisions, but then there are some consequences."

Djokovic was initially detained at an airport after arriving in Australia, while his status remained in limbo. His coach, Goran Ivanisevic, said it had been "not the most usual trip Down Under".

Spanish superstar Nadal has 20 grand slam titles, the same number that Djokovic and Roger Federer have brought up across their careers. They are locked in a race to finish with the most majors, and Federer, at 40, is battling back from injury and unlikely to compete at a slam before the US Open.

Australia's Prime Minister Scott Morrison tweeted on Thursday: "Mr Djokovic's visa has been cancelled. Rules are rules, especially when it comes to our borders.

"No one is above these rules. Our strong border policies have been critical to Australia having one of the lowest death rates in the world from COVID, we are continuing to be vigilant."

Nadal has some sympathy for Djokovic, but it appears to be limited.

"Of course, I don't like the situation that is happening," Nadal said. "In some way I feel sorry for him. But at the same time, he knew the conditions since a lot of months ago, so he makes his own decision."

Ricardas Berankis will face Rafael Nadal in the second round of the Melbourne Summer Set after beating Marcos Giron on Wednesday.

Nadal made his return after a five-month absence due to injury when he and fellow Spaniard Jaume Munar beat Sebastian Baez and Tomas Martin Etcheverry 6-3 3-6 10-4 in a doubles match in Melbourne on Tuesday.

The 20-time grand slam champion will be back in singles action against Berankis at Rod Laver Arena on Thursday after the Lithuanian qualifier dispatched American Giron 7-5 6-4.

Fifth seed Benoit Paire was trailing 4-6 6-3 5-2 to Henri Laaksonen when the Frenchman retired from the contest.

Alexei Popyrin and Jordan Thompson advanced on home soil, beating Stefano Travaglia 7-6 (7-5) 6-3 and Christopher O'Connell 1-6 7-5 6-4 respectively.

Munar beat towering South African Kevin Anderson 6-4 6-4, while Emil Ruusuvuori, Alex Molcan and Maxime Cressy also made it through.

Marin Cilic racked up the 550th victory of his career at the Adelaide International 1, defeating Thiago Monteiro 6-4, 7-6 (7-3).

Third seed Cilic will now come up against Laslo Djere, who was level at one set apiece with Corentin Moutet when the Frenchman was disqualified after reportedly swearing at the umpire.

Thanasi Kokkinakis fought back to oust Frances Tiafoe in the final match of the day, the Australian wild card winning 3-6 7-5 6-1.

Andy Murray stumbled out of the Melbourne Summer Set tournament after a first-round defeat to Argentinian Facundo Bagnis.

In his opening ATP Tour match of the year, three-time grand slam winner Murray slipped up 6-3 5-7 6-3 against Bagnis, a player who began the year with a 30-59 win-loss career record.

Left-hander Bagnis rose to the occasion on Rod Laver Arena to earn the scalp of the former world number one.

Murray, down at 134th in the rankings after another injury-hit year, is looking to make headway on that front in 2022 under new coach Jan de Witt, so that he can avoid having to take wildcards into tournaments.

He was allowed into this tournament by that back-door route, and has also been confirmed for an Australian Open wildcard, but the Scot could not find the form that saw him beat Rafael Nadal at an exhibition event in Abu Dhabi in late December.

Bagnis said of his win: "In the beginning it was a pleasure to play against Andy and right now to beat him is amazing. I'm really happy."

He added, according to the tournament website: "Yesterday, I came to see the stadium, to see it all around because the atmosphere is different when you play on any court outside… I enjoyed it a lot. It was so good for me."

Nadal was also back in action on Tuesday, playing his first match on the main tour since August as he teamed up with fellow Spaniard Jaume Munar for a doubles win.

A foot injury meant Nadal's 2021 season ended early, but he warmed up for singles tests that lie ahead by joining Munar for a 6-3 3-6 10-4 win over Argentinians Sebastian Baez and Tomas Martin Etcheverry.

At the Adelaide International 1 tournament, there was a notable first-round win on Tuesday for Australian Thanasi Kokkinakis, who saw off compatriot John Millman 6-4 6-3.

Kokkinakis, a major talent as a youngster, is battling to reassert himself on tour after injury troubles, and beating Millman put his name up in lights for at least one day.

He reflected afterwards on the battle it has taken so far, with last year spent largely living out of a suitcase on the second-tier Challenger Tour.

"It was a gruelling year travelling," said Kokkinakis. "I've played a couple of times [in Adelaide] but just in exhibitions, so to play a real meaningful tournament and beat such a quality opponent, a proven veteran like Johnny, means a lot. I played great, and the support was great, so I'm really happy."

Australian Open chief Craig Tiley wants Novak Djokovic to participate in Melbourne but will not ask the world number one to disclose any medical reason he has for being unvaccinated against COVID-19.

The first grand slam of 2022 begins on January 17, but it is unclear if reigning champion Djokovic will be competing.

The Serbian, a nine-time Australian Open winner, is yet to disclose his vaccination status.

Following guidance from the Victoria state government, all players, staff and spectators at Melbourne Park must have been fully vaccinated against coronavirus or hold a medical exemption.

Djokovic has been named on the list for the draw and is also due to represent Serbia at the ATP Cup in Sydney, which runs from January 1 to 9.

"If Novak shows up, he'll be vaccinated or have a medical exemption," Australian Open chief executive Tiley told the Australian Associated Press.

"If any player, fan [or] workforce is on site here, you're either vaccinated or you have a medical exemption that's approved and you're on the Australian Immunisation Register.

"That provides us with safety and an extra level of comfort on site.

"We want to have the best players here; I'd love to have Novak here. If he meets those conditions then great, if not, it's disappointing."

Tiley added he does not expect Djokovic to reveal any medical reason for which he may not have received the vaccine, should he receive a medical exemption to feature in the tournament.

"Medically, he doesn't talk to anyone about it. I'm not going to ask Novak that, it's none of my business," Tiley continued.

"[It's] his choice on his medical condition, it's his choice to keep personal and private like all of us would do with any condition we may or may not have. We are not going to force him or ask him to disclose that.

"[If he is here] I will know that he fulfils one of those conditions."

Rafael Nadal is set to play in Melbourne, though that is in doubt after the Spaniard tested positive for COVID-19 this week, following his appearance at the Mubadala World Tennis Championship in Dubai.

Tiley, however, believes Nadal will have recovered in time.

"I'm confident Rafa will be here," said Tiley. "Players that are testing positive now will complete a period of time until they are no longer infectious and they will be fine.

"If you are going to test positive and you want to play the Australian Open, your timing would be now."

Tokyo Olympics gold medalist Belinda Bencic has tested positive for COVID-19 ahead of next month's Australian Open and is experiencing "severe" symptoms.

World number 23 Bencic returned a positive test, along with Ons Jabeur, after competing at the Mubadala World Tennis Championship in Abu Dhabi.

The pair are the third and fourth players to have tested positive after travelling to the Abu Dhabi event, following 2021 US Open winner Emma Raducanu and 20-time major winner Rafael Nadal.

Bencic wrote on Twitter: "Unfortunately and even though I am fully vaccinated, I recently tested positive for Covid-19.

"I am currently isolating and taking all precautionary [measures] to get through this as best as possible as I am experiencing quite severe symptoms (fever, aches, chills)."

The Mubadala World Tennis Championship typically serves as a warm-up event prior to the Australian Open which is due to begin on January 17 in Melbourne.

World number 10 Jabeur, who defeated Bencic in Abu Dhabi, is experiencing "strong symptoms" and isolating in her native Tunisia.

Rafael Nadal has tested positive for coronavirus on his return to Spain, leaving his participation at the Australian Open in doubt.

The 20-time major champion played at the Mubadala Tennis Championship in Abu Dhabi last weekend and declared his mission a success despite consecutive defeats on his return from a foot injury.

Indeed, Nadal had only competed in two matches since losing to Novak Djokovic in the French Open semi-finals in June before testing his long-term foot problem against Andy Murray and most recently Denis Shapovalov.

However, the 35-year-old's plans to feature in the Melbourne ATP 250 ahead of the Australian Open in early January have suffered a setback after he tested positive for COVID-19 upon landing in his home country on Monday.

Nadal revealed the news on Twitter as he posted: "I wanted to announce that on my return home after playing the Abu Dhabi tournament, I have tested positive for COVID in the PCR test that was performed on me when I arrived in Spain.

"Both in Kuwait and Abu Dhabi we passed controls every two days and all were negative, the last being on Friday and having the results on Saturday.

"I am having some unpleasant moments but I hope that I will improve little by little. I am now homebound and have reported the result to those who have been in contact with me.

"As a consequence of the situation, I have to have total flexibility with my calendar and I will analyse my options. I will keep you informed of any decisions about my future tournaments!"

Nadal was eyeing the Australian Open, which starts on January 17, as his first major comeback, though he earlier admitted his entry was not guaranteed as he evaluated his foot injury and physical fitness.

"I cannot guarantee Australia one hundred per cent, because I need to go home and see how the body responds after these days," Nadal told reporters on Saturday. 

"I have time to make a decision. At this point in my career, I need to go day by day, study each movement well.

"I have been able to show a competitive level against good players even without being in perfect condition. There are things to improve but looking at things with perspective it has been a positive tournament [in Abu Dhabi].

"The main objective is to be healthy enough to do the things that I need to do and aspire to the objectives that I have always had. The illusion and passion continue to exist."

The ATP Tour event in Melbourne, which would be Nadal's first such tournament since August, is due to start on January 3.